There are two timebases, and triggering is done with a Schmitt trigger made of a 6U8 tube (in
early instruments) or a 6DJ8 tube (in late instruments).
The delaying timebase on the 535 (non-A) supports delays up to 100 milliseconds.
The 535-S1 supports delays up to 1 second.
The 535A supports delays up to 10 seconds.

The 535 is functionally the same as a 545, but with a simpler, non-distributed vertical amplifier.
Early 535s came in brown, square-cornered cabinets; in 1956 the cabinet became blue and round-cornered.
Early 535s had selenium rectifiers. The 535 has a thermal cutoff.

There is a rack-mount version, Types RM35 and RM35A. Starting in 1963, the 535A was
made with BNC connectors for the external trigger inputs. Prior to 1963, the external
trigger inputs used UHF connectors. 1972 was the last year that any version of the 535 was sold.
In 1973, the 54x series was still available, but nothing from the 53x series.

The first 535s had brown slide-out cases, then blue slide-out cases, and finally
blue cases with pop-off sides.

In Type 535 and 545 the total delaying sweep time is limited to 10 ms/cm.
If a total delaying sweep time in excess of 10 ms/cm is required, a
K535-S1 modification kit (Tek #040-063) which gives a maximum delay sweep
range of 1 s/cm. This kit is available for $40.00 in including a new
front panel.